tracking old VXIII vs new VX3

I know the older VXIII had only one errector spring in the turrets versus the new VX3 which has a two spring system. Did the the vxIII's still provide reliable tracking over regular repeated use or were they unreliable/didn't track properly.

Also I have read some commenst which suggest that a VX3 is virtually a MK4. is this truly the case or are the MK4 turrets still sturdier and therefore the most reliable option?